A. Field of the Invention
This invention relates to the field of art of automatic positioning control systems having solenoid operated valve assemblies.
B. Prior Art
Prior positioning control valve systems have been known which sense load on demand. Such positioning control systems have been particularly important in the contour following mobile equipment field such as, for example, in agricultural combines in which a heavy header is positioned. In this environment, it is important to provide load sensing with minimal complexity as well as fine control of flow to maintain the header within a necessary dead band while minimizing shock load to the header. While the prior art does disclose positioning control valve systems, it left much to be desired in valving complexity since the ability to sense load on demand has in the past been provided by either an extra valve or an extra land on a spool type control valve.
Accordingly an object of the present invention is a programmed valve system in which load sense is sensed without requiring a separate valve actuator or a separate land on a spool.